Let me clarify something for you about those miniboss timers, because i see this question come up quite a bit. The thing is, completing the main story doesn't actually change how quickly these tougher enemies come back (this helps maintain the game's intended challenge level). What's interesting is that the game handles post-game content differently - instead of faster respawns, you'll get entirely new challenges to tackle.

The miniboss Checkpoint option stays exactly the same as it was during the story (which is actually pretty helpful if you're practicing specific fights), and those berserker battles you've cleared will stay cleared, though you can always revisit their markers if you're looking to test your skills again. Something worth noting is that when you spot those remnants of asgard showing up, they're completely fresh encounters, not respawned versions of earlier fights.

Here's something that might be useful to know - if you're seeing enemies pop back up in certain areas, like the crater, it's usually tied to the day/night cycle rather than your story progress. These world mechanics stay pretty consistent throughout your journey, which helps keep the challenge feeling fair and predictable (especially helpful when you're hunting for specific resources or trying to complete those endgame challenges).